﻿// <copyright file="HuffmanSpec.cs" company="James Jackson-South">
// Copyright (c) James Jackson-South and contributors.
// Licensed under the Apache License, Version 2.0.
// </copyright>
namespace ImageSharp.Formats.Jpg
{
    /// <summary>
    ///     The Huffman encoding specifications.
    /// </summary>
    internal struct HuffmanSpec
    {
#pragma warning disable SA1118 // ParameterMustNotSpanMultipleLines

        /// <summary>
        ///     The Huffman encoding specifications.
        ///     This encoder uses the same Huffman encoding for all images.
        /// </summary>
        public static readonly HuffmanSpec[] TheHuffmanSpecs =
            {
                // Luminance DC.
                new HuffmanSpec(
                    new byte[]
                        {
                            0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0,
                            0, 0, 0
                        },
                    new byte[]
                            {
                               0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
                            }),
                new HuffmanSpec(
                    new byte[]
                        {
                            0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0,
                            0, 1, 125
                        },
                    new byte[]
                        {
                            0x01, 0x02, 0x03, 0x00, 0x04, 0x11,
                            0x05, 0x12, 0x21, 0x31, 0x41, 0x06, 0x13,
                            0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32,
                            0x81, 0x91, 0xa1, 0x08, 0x23, 0x42, 0xb1,
                            0xc1, 0x15, 0x52, 0xd1, 0xf0, 0x24, 0x33,
                            0x62, 0x72, 0x82, 0x09, 0x0a, 0x16, 0x17,
                            0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
                            0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38,
                            0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47,
                            0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56,
                            0x57, 0x58, 0x59, 0x5a, 0x63, 0x64, 0x65,
                            0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74,
                            0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x83,
                            0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a,
                            0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
                            0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6,
                            0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
                            0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2,
                            0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9,
                            0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
                            0xd8, 0xd9, 0xda, 0xe1, 0xe2, 0xe3, 0xe4,
                            0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf1,
                            0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
                            0xf9, 0xfa
                        }),
                new HuffmanSpec(
                    new byte[]
                        {
                            0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
                            0, 0, 0
                        },
                    new byte[]
                            {
                               0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
                            }),

                // Chrominance AC.
                new HuffmanSpec(
                    new byte[]
                        {
                            0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0,
                            1, 2, 119
                        },
                    new byte[]
                        {
                            0x00, 0x01, 0x02, 0x03, 0x11, 0x04,
                            0x05, 0x21, 0x31, 0x06, 0x12, 0x41, 0x51,
                            0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81,
                            0x08, 0x14, 0x42, 0x91, 0xa1, 0xb1, 0xc1,
                            0x09, 0x23, 0x33, 0x52, 0xf0, 0x15, 0x62,
                            0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34, 0xe1,
                            0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
                            0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37,
                            0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46,
                            0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55,
                            0x56, 0x57, 0x58, 0x59, 0x5a, 0x63, 0x64,
                            0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73,
                            0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a,
                            0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88,
                            0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
                            0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4,
                            0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2,
                            0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9,
                            0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
                            0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5,
                            0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe2, 0xe3,
                            0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
                            0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
                            0xf9, 0xfa
                        })
            };
#pragma warning restore SA1118 // ParameterMustNotSpanMultipleLines
        /// <summary>
        ///     Gets count[i] - The number of codes of length i bits.
        /// </summary>
        public readonly byte[] Count;

        /// <summary>
        ///     Gets value[i] - The decoded value of the codeword at the given index.
        /// </summary>
        public readonly byte[] Values;

        /// <summary>
        /// Initializes a new instance of the <see cref="HuffmanSpec"/> struct.
        /// </summary>
        /// <param name="count">
        /// The number of codes.
        /// </param>
        /// <param name="values">
        /// The decoded values.
        /// </param>
        public HuffmanSpec(byte[] count, byte[] values)
        {
            this.Count = count;
            this.Values = values;
        }
    }
}